6. High Pressure Discharge Lamps Content 6.1 Overview of Low Low- and High High-Pressure Pressure Discharge Lamps 6.2 Spectrum of a Hg Discharge 6.3 The High-Pressure Mercury Lamp (HP) 6 4 Phosphors for High-Pressure Mercury Lamps 6.4 6.5 The Electrode 6.6 The Electrode Feed Through 6 7 Types 6.7 T off R Reflectors fl t 6.8 Application of HP-Lamps 6.9 The High-Pressure Sodium Lamp (HPS) 6.10 Application of HPS Lamps 6.11 Metal-Halide Lamps (MH) 6.12 Photometric Data in Comparison 6.13 Applications of MH Lamps 6.14 UHP-Lamps p 6.15 New Developments Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 1
6.1 Overview of Low- and High-Pressure Discharge Lamps HID = High Intensity Discharge Hg low-pressure (TL)
Hg high-pressure (HPMV = high pressure metal vapour)
Hg low-pressure (CFL)
Na high-pressure (HPS = high pressure sod.)
Na low-pressure (SOX)
Metal-halide high-pressure (MH)
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 2
Emissionsspektrum von Hg 6.2 Spectrum of Hg Discharges Energy level scheme of Hg Ionization level (~ 10.4 eV) 10
Schematic emission spectrum of a Hg-discharge at a low pressure [~ mbar] 254
6(3D1) 7(3S1)
5466 5777
6(3P1)
4088 4366
6(3P2)
5
3133 3666
1185
6(1P1)
1185 nm
Level energy y [eV]
7(1S0)
6(3P0)
200
300
400
500
600
[nm] 0
6(1S0)
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 3
200
300
500
in nm
100 lm/W
60
20
600
546 577
3313
408 200
254
1885
5 546 5577
4 408 4436 400
Phosphor P
[lm/W]]
100
3 313 3366
185
Pressure increase
436
366
254
6.2 Spectrum of Hg Discharges
300
400
500
in nm
600
Pressure dependence of the lumen output 60 lm/W Why is this of interest for lamps? Good imaging properties High luminance
20 lm/W 10 bar
Incoherent Light Sources Prof. Dr. T. Jüstel
1 bar
Pressure Chapter High Pressure Discharge Lamps Slide 4
6.2 Spectrum of Hg Discharges Measured spectra of water-cooled capillary mercury discharge lamps P = 25 atm atm..
P = 30 atm. atm.
P = 100 atm atm..
Source: W. Elenbaas, QuecksilberdampfHochdrucklampen (1966) Incoherent Light Sources Prof. Dr. T. Jüstel
P = 150 atm atm.. Chapter High Pressure Discharge Lamps Slide 5
6.3 The High-Pressure Mercury Lamp (HP) Evacuated outer bulb Melting Electrode
Burner (Hg, noble gas = starting Gas, mostly Xe)
Ballast Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 6
6.4 Phosphors for High-Pressure Mercury Lamps 5
Inte ensity [a.u.]
4
3
2
1
0 400
500
600
700
800
Wavelength [nm]
= 60 lm/W
Ra = 20 Lifetime = 20.000 h Incoherent Light Sources Prof. Dr. T. Jüstel
Blue white light due to the Blue-white lack of red radiation in the emission spectrum Solution: Phosphor! Chapter High Pressure Discharge Lamps Slide 7
6.4 Phosphors for High-Pressure Mercury Lamps 5
Plasma Relativve Intensity [a..u.]
4
3
Phosphor
2
1
0 400
Suitable phosphors (Sr,Mg)3(PO4)2:Sn Mg4GeO5.5F:Mn YVO4:Eu Y(V,P)O4:Eu
500
600
700
Wavelength [nm]
620 nm 660 nm 620 nm 620 nm
Broadband emission Line emission Line emission Line emission
= 60 lm/W
Ra = 50 Lifetime = 20.000 h Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 8
800
6.4 Phosphors for High-Pressure Mercury Lamps Sn2+ , Mn4+ phosphors as UV Red converter
Luminescence spectra of (Sr,Mg)3(PO4)2:Sn 1,0
max = 620 nm
QE254 = 79 % RQ254 = 5% x = 0.549 y = 0.426 LE = 150 lm/W
Re elative intensity
0,8
0,6
0,4
0,2
Intensiity
0,0 100
Emission spectrum Excitation spectrum Reflection spectrum 200
300
400
500
600
700
800
Sample U2024
W Wavelength l th [nm] [ ]
Luminescence spectra of Mg4GeO5.5F:Mn Emission spectrum Excitation spectrum Reflection spectrum
1,0
Relative intensity
0,8
[nm]
Problem: Low lumen equivalent i off these phosphors Incoherent Light Sources Prof. Dr. T. Jüstel
max = 658 nm
QE254 = 81 % RQ254 = 7%
0,6
x = 0.713 y = 0.287 LE = 80 lm/W
0 0,4
0,2
0,0 100
200
300
400
500
Wavelength [nm]
600
700
800
Sample U601
Chapter High Pressure Discharge Lamps Slide 9
6.4 Phosphors for High-Pressure Mercury Lamps YVO4:Eu3+ phosphors - Thermal behavior Excitation spectra of YVO4:Eu U737025C U737075C U737150C U737200C U737250C U737300C U737330C
Emission in ntensity [a.u.]
0,25
0,20
0,15
0,10
0,05
0 00 0,00
monitored at 619 nm 250
300
350
400
Wavelength [nm]
Emission spectra of YVO4:Eu U737025C U737075C U737150C U737200C U737250C U737300C U737330C excitation at 300 nm
Emission intensity [a.u.]
80000
60000
40000
600
650
700
integral 254 nm exc. Integral 300 nm exc. Integral 350 nm exc.
7 6 5 4 3 2 1 0 0
50
100
150
200
250
300
The luminous Th l i efficacy ffi under d UV-A UV A excitation it ti increases i up to about 300 °C Reason: Increase in spectral overlap 750
Wavelength [nm]
Incoherent Light Sources Prof. Dr. T. Jüstel
350
Temperature [°C]
20000
0 550
Luminescence intensity as a function of t temperature t and d excitation it ti wavelength l th
8
Relative em mission intensity
0,30
Chapter High Pressure Discharge Lamps Slide 10
6.5 The Electrode Hg low-pressure
Hg high-pressure
0.5 cm
1.0 cm
36 W I = 0.36 A
400 W I=4A
Tungsten + emitter BaO / SrO / CaO
Tungsten + emitter BaO / SrO / Y2O3 / ThO2
T = 1350 K
T = 2000 - 3000 K
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 11
6.6 The Electrode Feedthrough Problem: Different thermal expansion coefficients Quartz (1000 °C) Plasma
Tungsten
Incoherent Light Sources Prof. Dr. T. Jüstel
Very thin Mo- or Nb-foil
SiO2 W Mo
= 0.5*10-6 K-1 = 4.3*10-6 K-1 = 2.8*10-6 K-1
Molybdenum
Chapter High Pressure Discharge Lamps Slide 12
6.7 Types of Reflectors Parabolic reflectors
Elliptical reflectors
y = x2
Focal point (light source)
An ellipse has two focal points
Only when the light source is point like
HID lamps HID-lamps
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 13
6.8 Application of HP-Lamps In street lighting (outdoor lighting)
= 60 lm/W
Ra = 50 Lifetime = 20.000 h P = 100 W - 2000 W Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 14
Na low-pressure Lamp (0.01 mbar)
300
200
400
500
600
in nm
in lm/W
Pressure increase
700
589 nm
589 nm
6.9 The High-Pressure Sodium Lamp (HPS)
Na high-pressure Lamp (100 mbar)
300
400
500
600
in nm
700
Pressure dependence of the lumen output 120
10 bar Incoherent Light Sources Prof. Dr. T. Jüstel
1 bar
Na-pressure Na pressure Chapter High Pressure Discharge Lamps Slide 15
6.9 The High-Pressure Sodium Lamp (HPS) Problem: Na reacts at high temperatures with the quartz glass wall 4 Na + SiO2 2 Na2O + Si Solution: Transparent, high temperature resistant material, which does not react with Na
Crystal
Al2O3-ceramics (corundum): MgO, CaO, B2O3-Additives (DSA = densely sintered alumina)
20 m
Polycrystalline structure Pressure, 1200 °C
Nb or Mo Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 16
6.9 The High-Pressure Sodium Lamp (HPS)
589 nm n=3 n=2 n=1
Incoherent Light Sources Prof. Dr. T. Jüstel
Widening of the Na-line and selfabsorption leads to a spectral hole in the emission spectrum at around 589 nm pNa = 150 mbar (saturated) pHg = 1000 mbar (buffer gas) pXe = 100 mbar (start gas) = 90 - 120 lm/W Ra = 20 – 50 (p (pressure dependent) p ) Tc = 1930 K (589 + x) nm (red-shift) (589 - x) nm (blue-shift)
Chapter High Pressure Discharge Lamps Slide 17
6.10 Application of HPS Lamps Architectural and street lighting
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 18
6.11 Metal-Halide High-Pressure Lamps In 451
Tl Na 535 589
Filling: NaI - TlI - InI SnBr2 - SnI2 NaI - DyI3 (SSTV) NaI - ScI3 (automobile headlight) Goal: High & color rendering
SnBr/SnI-molecule emitters
DyI-molecule emitters
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 19
6.11 Metal-Halide High-Pressure Lamps HPI (High Pressure Iodide) lamps
451 nm (In) 535 nm (Tl) 589 nm (Na)
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 20
6.11 Metal-Halide High-Pressure Lamps Spectrum of a MH lamp 0.30
Tl 0.25
Hg / NaI / TlI / DyI3 / Ar P = 75 W
V
Na
I [W W/nm]
0 20 0.20
Hg
Prad / P 60 % Prad,vis rad vis / P 33 %
Na
0.15
0.10
Hg 0.05
0.00 350
atomic line and molecular radiation 400
450
500
550
600
650
700
750
[nm] Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 21
800
6.11 Metal-Halide High-Pressure Lamps Filling of metal halide lamps Lamp p starting g (starting g ggas) Noble gases: Ar or Xe (xenon lamps) → Penning-effect Radioactive substances: 85Kr, 147Pm Operating voltage • Hg • Trend towards the substitution of Hg (environmental aspect) → Zn Light emission • Hg • Me-halides (Me = Na, In, Tl, Sc, Sn, Dy, ...)
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 22
6.12 Photometric Data in Comparison HP (Hg)
HPS (Na)
MH
Improvement -
(lm/W) 60
Ra 20
Color temperature Tc [K] 6000
+ phosphor
60
50
3800
-
60 - 130
20
2000
Xe-pressure
80 - 150
20
2000
Na-pressure
60 - 90
60
2200
HPI (NaI-TlI-InI) 70 - 80
70
3800 - 4200
SnBr2-SnI2
70
90
NaI-DyI3
75 - 80
90
3800 - 5600
NaI-ScI3
80 - 90
75
3600 - 4200
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 23
6.13 Applications of MH Lamps HPI (NaI-TlI-InI)
Street lighting Architectural lighting Sports field lighting
Tin
Older type of lamp is replaced by MH
NaI-DyI3 NaI ScI3 NaI-ScI
Sports field lighting Shop lighting Studio-stage-TV (SSTV) Automotive headlights
NaI ScI3 + Hg + Xe (blue) NaI-ScI
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 24
6.13 Applications of MH Lamps SSTV market k t = St Stage-Studio-TV St di TV Reflector
Spherical mirror
f
Fresnel-lens
Farbtemperatur = 5600 K Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 25
6.13 Applications of MH Lamps In the „beamer“
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 26
6.13 Applications of MH Lamps Construction of a beamer A projector is actually a slide projector (diascope)!
Lamp at the focal point in a parabolic reflector
Collecting lens
Slide
In a beamer the slide is replaced by a small LCD screen or by a DMD ((Digital g Mirror Device)) Incoherent Light Sources Prof. Dr. T. Jüstel
Projection screen
Chapter High Pressure Discharge Lamps Slide 27
6.13 Applications of MH Lamps Operating principle of a LCD (Liquid Crystal Display) LCDs are based on liquid crystals, which rotate the polarization plane of polarised light by a rotational angle ά
Polarizer-foil P Liquid crystal cell (with ITO) Analyzer foil (perpendicular to P) U
Pixel on for U = 0 Pi l off Pixel ff for f U>0
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 28
6.14 UHP-Lamps Requirements for light sources for projectors • If possible punctual A lot of light from a small volume • High luminance (light density ) High Hg-pressure
400
546 n nm 577 nm m
436 nm m
408 nm
UHP = Ultra High Pressure (Performance) Approx. 200 bar Hg, electrode separation ~ 1 mm Strong pressure-broadened lines of Hg
500
Incoherent Light Sources Prof. Dr. T. Jüstel
600
700
800 Chapter High Pressure Discharge Lamps Slide 29
6.14 UHP-Lamps Components of UHP-Lamps
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 30
6.14 UHP-Lamps Design of UHP-lamps
Description of UHP-lamp by • Chemical equations Vapor pressure of metal halides Disintegration of the metal halides in the plasma •Temperature distribution in the plasma Energy balance Loss via radiation Loss due to chemical energy Loss due to heat Convection (flow)
Heat conduction
• Convection equation = Navier-Stokes-Equation
2h 2h 0 2 2 x y
Potential : h z
u w
• Energy balance of the electrodes and the wall Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 31
6.14 UHP-Lamps
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 32
6.15 New Developments Sulfur lamp: In 1990 the first discharge lamp based on a molecular sulfur discharge (S4 – S8) was develop
The energy coupling into the discharge takes place by means of a microwave generator (magnetron), g ( g ), because electrodes can not be used Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 33
6.15 New Developments S lf lamp: Sulfur l To T generate t a very large l luminous l i flux fl
Typical operating parameters Input power: 1.400 W Ball diameter: approx. 30 mm Luminous flux: 135000 lm Color temperature: 5700 K Starting time: 25 s Lifetime (lamp): 60.000 h Lifetime (magnetron): 20.000 h Light output: 95 lm/W
Light source with extremely high light output, about 140000 lm (~ 40 fluorescent tubes) and (almost) pure-white light (emission band of S8, …. , S2 molecules) Efficiency: Problems:
Similar to fluorescent lights (thus 90 - 100 lm/W) EMC and lifetime of the microwave generator
Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 34
6.15 New Developments S lf lamp: Sulfur l Mechanism M h i off light li ht generation ti Emission E i i from f molecules l l , e.g. S2
C. W. Johnston, Transport and equilibrium in molecular plasmas: The sulfur lamp, Technische Universiteit Eindhoven, Eindhoven 2003 Incoherent Light Sources Prof. Dr. T. Jüstel
Chapter High Pressure Discharge Lamps Slide 35
6.15 New Developments Substitution of Hg by Zn (e.g. in automotive headlamps) Zn/Ar Discharge
Zn/Ar/metal halide Discharge
1,0
0,8 472
0,6 636 468
0,4
0,2
0,30
Wel = 75 W LE = 280 lm/W x = 0.436, y = 0.387 Tc = 3000 K Efficacy = 85 lm/W = 0.33 Wopt/Welektr Ra8 = 80
0,25
Emis ssion intensity [a.u.]
Emisssion intensity [a.u.]
481
Wel = 75 W LE = 114 lm/W x = 0.228, y = 0.227 Tc = 34000 K Efficacyy = 20 lm/W = 0.174 Wopt/Welektr Ra8 = 0
0 20 0,20
0,15
0,10
0,05
Ce3+ Luminescence 0,0 400
500
600
700
File: Zn discharge lamp (60-75-90W)
Wavelength [nm]
Energy efficiency Ra Incoherent Light Sources Prof. Dr. T. Jüstel
800
0,00 300
400
500
600
700
Wavelength [nm]
Zn-Ar 20 llm/W /W 17% 0
800
File: Zn discharge lamp (60-75-90W)
Zn-Ar-metal halide 85 llm/W /W 33% 80 Chapter High Pressure Discharge Lamps Slide 36